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A destructive tornado in North Carolina Friday ended an unusual delay in stronger tornado activity in 2014, cementing a new record for a lack of stronger tornadoes-to-date in 2014.
On Saturday, officials at the National Weather Service in Morehead City, North Carolina, announced that one of Friday's tornadoes in eastern North Carolina rated an EF3 on the Enhanced Fujita Scale.
The April 25 tornado marked the latest wait by far for the first such tornado in any year in modern records dating to 1950, according to theUniversity of Alabama-Huntsville.
March 31, 2002 was the previous record latest date of the season's first F3 or EF3 tornado. The Enhanced-Fujita scale replaced the original Fujita Scale on Feb. 1, 2007.
Older, likely incomplete historical records compiled by tornado historian Tom Grazulis in the bookSignificant Tornadoes 1680-1991 indicate that the last year whose first F3 tornado came later was 99 years ago, when the first F3 of 1915 (rated retroactively by Grazulis) came on May 1.
The last U.S. tornado of EF3 intensity or stronger had been during the Nov. 17, 2013 outbreak in the Midwest, making it a a stretch of five months and eight days between EF3 tornadoes in the U.S.
According to statistics compiled by severe weather expert, Dr. Greg Forbes (Twitter | Facebook), the period from January through March averaged between eight and nine tornadoes of F/EF3+ intensity in the period 1950-2012.
While we have had several episodes of severe thunderstorms in 2014, we've been fortunate enough to avoid the volatile combination of low-level wind shear (rapidly changing wind direction and speed with height) and strong instability (very warm and humid air near the surface topped by cold, dry air aloft) known to spawn large, destructive tornado outbreaks.
As you can see in the pie chart below, while stronger tornadoes (EF3+) are more rare, they make up a large majority of tornado fatalities each year.
April and May lead with 10-11 F/EF3+ tornadoes each month, on average, according to Dr. Forbes.
Keep in mind while current tornado counts in 2014 are roughly 72 percent below the average-to-date through April 25, destructive outbreaks do occur in years with fewer overall tornado counts.
Both 2012 and 2013 featured at least 400 fewer U.S. tornadoes than the 10-year average. Despite fewer tornadoes, destructive twisters still occurred:
- Mar. 2-3, 2012: EF4 in Henryville, Ind.; EF3 in West Liberty, Ky.
- May 15, 2013: EF4 in Granbury, Texas
- May 19-20, 2013: EF5 in Moore, Okla.
- May 31, 2013: EF3 in El Reno, Okla.
- Nov, 17, 2013: EF4 in Washington, Ill.
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